Alfalfa is a VP8 encoder and decoder, implemented in explicit state-passing style and developed by the Systems and Networking Research group at Stanford University. It is the basis for the ExCamera and Salsify systems. Almost all the source files are licensed under the BSD 2-clause license. Alfalfa links against x264 to compute the SSIM (quality) of frames. Because this library is distributed under the GNU GPL 2+, so is Alfalfa's ssim.cc file, and the overall Alfalfa package.